Carburetor structure



Dec. 6, 1938. f l. E.v cor-'FEY 2,139,356

` l CARBURETOR STRUCTURE Filed July 7, 195e 2 sheets-sheet 2 l5 I Y f l i 'ff :T1 '7i' l fw V1' f 4i? f I'IH- Qhf .3 1' 5s f-- l f8 1,*"9 ,'n \ZZ .TFA/525,1 f? L I INVENTOR, Irl/en E. Coffy- A TTORNEY.

Patented Dees, 1938 PATENT oFFlcE 2,139,356 CARBURETOR STRUCTURE Irven E. Coffey, St. Louis, Mo., assigner to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application .July '7, 1936, Serial No. 89,311

12 Claims.

This invention relates to carburetors for internal combustion engines and consists particularly in novel construction and arrangement of thermo-responsive choke control devices.

In a well known form of automatic choke device for automative carburetors, a housing mounted on the carburetor barrel encloses a thermostat which is connected by suitable means to the choke valve. In order to insure sufficiently rapid heating of the thermostat after the engine has been started so that the proper mixture will be'supplied at all times during the warm up, the housing communicates through a separate tube with a stove secured to the exhaust manifold and suction means is provided for drawing heated air through the housing. With this arrangement,

substantial heat is" lost duringconduction from the stove vand connection tube. Moreover, the heater and heater connection must be applied and adjusted separatelyl from the carburetor.

An object of the present invention is to provide improved means for insuring rapid heating of the thermo-responsive choke control means in an automatic choke carburetor. Another object is to utilize exhaust gases for heating the thermostat. Another object is to form heating and suction passages for the thermostat` housing integral with the barrel of the carburetor thus eliminating separate outside connections. Still another object is to provide a novel double-walled thermostat housing in which the space between the walls may be utilized as a chamber for passing exhaust gases in the immediate vicinity of the thermostat, or as a dead air space for insulating the inner portion of the housing which encloses the thermostat. These objects and other more detailed objects hereafter appearing are attained substantially by the structures illustrated in the accompanying drawings in which: Figure 1 is a side View of an automotive carburetor and part of an associated manifold, the upper portion of the figure being sectioned substantially on line Ia-Ia of Figure 3 and the lower portion being broken away and sectioned substantially on line I-I of Figure 3.

Figure 2 is a view of a part of the carburetor taken at 90 degrees toFigure l, the cover portion of the thermostat housing being sectioned on the center line thereof.

Figure 3 is a top view and section taken substantially on line 3-3 of Figure 2.

Figure 4 is a view of a carburetor somewhat as in Figure l, but showing a modification.

The carburetor in Figures l to 3 comprises a (Cl. 12S-119) constant level fuel bowl and a barrel or body portion forming a downdraft intake conduit including air horn portion 2, mixing chamber 3 which may include one or more venturis, and outlet portion 4. A vchoke valve 5 is pivotally mount- 5 ed in the air horn on shaft 5a. anda throttle valve 6 is pivoted in the lower portion of the barrel on shaft 6a. A suitable crank (not shown) is secured to shaft 6a for manual operation of the throttle valve. A flange 1 on the lower portion l0 of the carburetor is secured. by bolts 8 to a flange 9 on the riser portion I0 of intake manifold Formed integral with the intake manifold is a heater or hot spot structure I2 communieating with the exhaust manifold, a, part of Y which is shown at I3, in a manner to conduct exhaust gases through spaces |4 around the intake manifold for heating the fuel mixture immediately before it enters the carburetor.

Mounted on the outside of the air horn is a thermostat housing including a base portion |51 and lcover portion I6 secured thereto'dby screws I1. A stud I8 projects. from the center portion of the inner wall IGa of the housing and mounts a spiral, bi-metal thermostat I9. Rigid with choke shaft 5a within the housing is a crank 20 having an outward projection 20' about which extends a hook I9 on the outer end of the thermostat for controlling the choke valve, responsive to temperature conditions, in a well vknown manner. Crank 20 is also connected at 2| to a piston 22 mounted for oscillation in cylinder 23 I formed in the housing base portion I5. The thermostat housing is carried in part by choke shaft 4 and in part by a lateral extension 24 on the 35 body of the carburetor. Extending along the left hand side of the carburetor body, Figure l, is a passage 25 formed in a rib 25a integral with the body and con- -nected at its lower extremity with passage 26 in 40 the manifold riser portion I0, which in turn opens into the exhaust gas space I4. At its upper end, passage 25 has a portion 21 extending at right anglesthereto through the body extension 24 and then upwardly and communicating with inclined passage 28 in the housing base portion. Passage 28 has an opening 29 into the space between the walls |6a and Ilib of the housing cover portion. y

l Also extending along the carburetor body portion, but substantially on the right hand side thereof, Figure 1, is a rib 30 drilled to form a passage 3| communicating at its lower end through hole 32 with the intake conduit posterior to the throttle valve. At its upper end, passage 3| has 55 diverging branches 33 and 34 formed within the body extension 24 Passage 33 communicated through an apertured boss 35 with the interior of cylinder 23, and passage 34 communicates with passage 36 which has an opening 31 between the Walls of the thermostat housing.

As is well known in the art, a substantial difierence in pressure will exist, during operation of the engine, between the intake and exhaust manifolds, This causes exhaust gases to be drawn from space I4 in the hot spot through passages 26, 25, 21 and 28 into the space between the walls |6a and |6b of the thermostat housing cover portion. These gases circulate around the housing, being sealed from the thermostat by inner wall I 6a, and are drawn through opening 31 and passages 36, 34 and 3| into the interior of the carburetor and the intake manifold.

Obviously greater quantities of hot gas will be drawn through the housing when the throttle is partially closed or closed and theengine idling due to the higher suction in the intake conduit at such times. This is an advantage since rapid warming of the thermostat is desirable when the engine is warming up after a cold start. Suiiicient gases will be drawn through the heated chamber at all times during operation of the engine to hold the choke open. If desired, suitable means may be provided for cutting down the quantity of gases drawn through the housingl after the choke has fully opened so as-to prevent excessive heating of the thermostat.

Suction in passage 3| is also communicated to cylinder 23 and piston 22 which function to open the choke valve against the force of the thermos tat particularly when the engine :tires after cranking.

Figure 4 illustrates a thermostatic housing having double walls 33a and 33h and enclosing a thermostat (not shown) as in the previous form. A threaded boss 39 on the housing base portion 40 is connected to a conduit 4| which at its lower end communicates with a suitable stove (not shown), associated with the exhaust manifold. 'I'he inside of the housing also preferably communicates with the intake manifold for drawing ho't air therethrough for heating the thermostat. A dead air space 42 between the walls of the housing cover portion provides substantial insulation against the loss of heat.

The construction ot the carburetor in both l forms. andthe automatic thermoand suction-responsive choke control are well known in the art and accordingly are not described in detail.

` These parts and also the heating and housing means may b e modied as will occur to those skilled in the art. For instance exhaust gases may be passed into the inner chamber in Figures 1 to 3, but this is not desirable due to the corrosive eifect of the exhaust gases, and also hot air from a stove may be circulated through the outer chamber. The exclusive use of all such modifications as come within the scope of the appended claims is contemplated.

1. In an internal combustion engine,"an exhaust passage, an intake conduit, `a choke valve 'in said conduit, a thermo-responsive control ele- 4ment for said.valve,

a chamber adjacent said element, and separated therefrom, vand connections between said chamber and said passage and said chamber and said conduit for utilizing pressure diiierencesin slide and said conduit the annular gas chamber in to draw heated exhaust gases into the vicinity of said element.

2. Structure as specied in claim 1 further including a housing for said thermo-responsive element, said chamber and said housing being substantially sealed from each other.

3. Structure as speciiied in claim 1, in which said chamber extends substantially around said thermo-responsive element.

4. Structure as speciiied in claim 1, further including a throttle valve in said conduit, said chamber communicating with said conduit posterior to said throttle valve.

5. In combination, an internal combustion engine carburetor having a choke valve, a thermoresponsive control element for said valve, and a vmanifold structure and said carburetor barrel part.

7. In an internal combustion engine, and intake conduit, an exhaust passage extending at valve in said conduit, a thermostat for controlling said valve, a housing for said thermostat having a -cover with spaced walls said thermostat being sealed vfromthe space between said walls, a duct leading from said exhaust base portion into thermostat having a cover with spaced walls and a base portion, said thermostat being sealed from the space between said walls, and a duct leading from said exhaust passage through said housing base portion into the space betweenv said cover walls for heating said thermostat, said heating duct leading from the portion of said exhaust passage directly associated'withv said intake conduit.

9. In combination, an internal combustion engine carburetor having a choke valve, thermoand suction-responsive control means yfor said choke valve, a housing for said control means, a heating chamber adjacent said housing and substantially sealed therefrom, a connection between said chamber and said exhaust passage, and communicationbetween said intakeconduit and said suction-re ponsive means and said conduit and said heating chamber. 10. The combination of elements specified in- 2,139,350 3 and extending a substantial distance therealong for conducting hot gases from said manifold structure into the vicinity of said control element. l

12. Structure as specified in claim 11 further lne intake manifold structure. a carburetor iniuding a mixture conduit connected to said strucure and a choke valve therein, an exhaust maniold having a part forming a portion of said inzake manifold structure for heating the same, a l

merino-responsive control element for said choke including a suction passage also formed in th( valve and substantially spaced from said intake l wall of said conduit.

manifold structure, and a heating passage for IRVEN E. COFFEY. said element :formed in the wall of said conduit 

